1. Field of the Invention
The present invention is concerned with an insulative tube structure equipped with an integrally secured, external metallic element such as an elongated lock bar, and a method of manufacturing the tube structure. More particularly, it is concerned with such an insulative unit wherein the metallic attachment is formed as an essentially monolithic part of the tube sidewall by having been embedded in the latter and retained in fixed disposition thereon prior to and during final curing of the resin.
2. Description of the Prior Art
In the manufacture of electrical hot line tools, use is commonly made of elongated, insulative tubes formed of synthetic resin material such as resin (e.g., polyester or epoxy) impregnated fiberglass. inasmuch as these tools are designed for use by linemen working on energized conductors and equipment, it will be appreciated that the insulative integrity of the tubes used in the tools must be very high.
In many cases hot line tools of the type described are equipped with metallic attachments on at least certain of the synthetic resin tubes. For example, some devices of this type are equipped with elongated, metallic lock bars which secure movements of a control rod. While it would be possible to attach such lock bars by means of metallic fasteners through the tube sidewalls, it will be appreciated that this is undesirable from the standpoint of electrical insulative qualities. At the same time, it is vitally necessary that the lock bars be firmly secured to the associated tubes, in order that the lock bars serve their intended function.
Patents describing various methods of attaching metal articles to substrates such as synthetic resin bodies include the following: U.S. Pat. Nos. 4,114,962, 3,700,512, 3,925,132, 3,775,207, 3,116,547, 2,666,007 and 3,047,191.